The present invention relates to a switched-mode power supply device. The present invention also relates to the use of such a switched-mode power supply device.
The background of the invention is firstly formed by common switching topologies for realizing switched-mode power supplies which enable improved power densities with smaller dimensions and a relatively compact and inexpensive configuration. Thus, for example, it is known from the prior art to assume a resonant converter according to the LLC topology, wherein an LLC resonant converter such as this fundamentally enables a high degree of efficiency but, in particular in the case of electrical consumers provided at the output which have a high power consumption (that is to say having a high electrical load), shows strong non-linear system perturbation effects.
It can also be assumed from the prior art and in relation to the technical background to provide switched-mode power supplies with regard to their system perturbance with the help of so-called power factor correction (PFC), wherein such technologies are usually provided on the primary side of the transformer provided in the switched-mode power supply in order to shape the current profile to be as sinusoidal as possible and to reduce the one reactive current component. In this respect, so-called passive PFC applications are known, usually realized as harmonics filters or mains filters with high inductivity for power factor correction; however, so-called active PFC applications, which, as switching stage upstream of the converter, actively readjust the current drawn to the temporal profile of the sinusoidal mains voltage, are also likewise assumed.
However, in particular, active PFCs such as this are disadvantageous for an optimum degree of efficiency of a switched-mode power supply device.
The switched-mode power supply device according to DE 10 2012 111 853, which is applicable as generic prior art, from the applicant already achieved an optimization in this outlined technical voltage field: by means of a control unit which is typically realized as integrated (or programmable) circuit component, on the one hand, an effective power factor correction is achieved (without the need for a separate PFC network or further discrete components for such a realization) by said functionality (in the integrated component) being combined with a current regulating functionality for the output current and a suitable actuation for the converter. In addition to a significant reduction in complexity in terms of hardware or components, the possibility of performing flexible parameterization of the switched-mode power supply system by suitable programming and thus of achieving a high universality of the device with good regulation and converter properties is advantageous in the case of said technology which forms the starting situation for the present invention, wherein a generic device such as this is then suitable, in particular, for current regulation processes in connection with LED illuminants as output-side load, but can also be additionally used in a flexible manner.
However, the technology disclosed in DE 10 2012 111 853 is also still potentially in need of improvement in certain operation situations. Thus, it has become apparent, particularly during the practical testing of said technology, that disturbances which are very large or which follow one another in quick succession in the AC voltage input signal lead to disadvantageous influences on the output current, despite the disturbance-suppression measures which have already been implemented.
The double signal graph of FIG. 3 for practical operation of the device described in DE 10 2012 111 853 (wherein the lower curve 20 compares the profile of the AC voltage input signal with the profile 30, which is proportional to time, of the output current, in the case of typical signal amplitudes and resolutions of the signal according to the key) shows such an influence: it becomes apparent that a voltage drop (owing to disturbances) of approximately 70 volts in a period (fifth signal period of the voltage signal 20) leads to a significant influence on the output current 30, caused in particular by the fact that, in the principle disclosed in DE 10 2012 111 853, the signal shape of the AC voltage input signal 20 is used in order to derive therefrom the sinusoidal profile for the output current. However, since in the case of the disturbance illustrated in FIG. 3, provided that a large signal-shape impairment occurs, this leads to a variation in brightness of an LED load which is usually controlled on the output side, it being possible to detect said variation in brightness by the selective drop of the output current 30 according to FIG. 3, and which in turn is visually discernible and is perceived as a disturbing lighting effect.